On an existing wavelength division multiplexing (Wavelength Division Multiplexing, WDM) network, center frequencies of optical signals with different wavelengths are distributed according to a fixed optical frequency grid (Optical Frequency Grid, OFG). Refer to FIG. 1, in which a commonly used 50 GHz grid (Grid) on an existing WDM network is taken as an example. Regardless of whether a bit rate of signals is 100 Gbit/s, 40 Gbit/s, or 10 Gbit/s, center frequencies of the signals are distributed strictly according to the 50 GHz grid.
As data traffic rapidly increases, a bit rate of signals on the WDM network further increases to 400 Gbit/s, or even to 1 Tbit/s. A signal spectrum width of these high rate signals may exceed 50 GHz. As a result, these signals cannot be transmitted on a network that is designed according to a fixed 50 GHz grid. In this case, a feasible method is to use a grid with a wider spacing, such as a 100 GHz grid. However, if hybrid transmission needs to be performed for both relatively low rate signals and high rate signals, the relatively low rate signals may also occupy a 100 GHz optical frequency slot (Optical Frequency Slot, OFS), which wastes spectrum resources in an optical fiber.
Currently, a flex grid (Flex Grid) technology is used in the prior art, which allows a channel of optical signals to occupy multiple consecutive OFSs. Refer to FIG. 2, in which signals with a bit rate of 100 Gbit/s occupy a spectral bandwidth of 50 GHz, signals with a bit rate of 400 Gbit/s occupy spectral bandwidths of 75 GHz to 87.5 GHz, and signals with a bit rate of 1 Tbit/s occupy spectral bandwidths of 150 GHz to 200 GHz. A specific implementation method may be as follows: 12.5 GHz is used as an OFS unit, signals with the bit rate of 100 Gbit/s occupy 4 consecutive OFS units, signals with the bit rate of 400 Gbit/s occupy 6 to 7 consecutive OFS units, and signals with the bit rate of 1 Tbit/s occupy 12 to 16 consecutive OFS units.
In the flex grid technology, the OFSs occupied by a channel of optical signals are consecutive and concatenated, that is, they are connected together. For example, this may be seen from a schematic diagram of an optical signal spectrum on an existing flex grid network, as shown in the FIG. 3. After cross transmission is performed through multiple nodes during network transmission, a large number of OFS fragments are generated, which causes messy distribution of an optical signal spectrum in an optical fiber and reduces the utilization of spectrum resources.